Improvement in tips for switch-cords



BEST AVAlLABLE 00F- T. B. DOOLITTLE. Tips for Switch Cords.

No. 208,969. Patented Oct. 15,1878.

BEST AVAlLABLE COP -U ITED STATES PA'I ENTO ICE 'lI-IOMAS 1:.noomr'rrln, or BRIDGEPORT, eons, Assrenon, BY Mus-nu ASSIGNMENT. T0'nuennn r. PHILLIPS, or rnovmnncn, n. I.

IMPROVEMENT m TIPS Foaswl'l'ou-coaosJ -f Specification forming part ofLetters Pat-ent No. 208,969, dated October 15, 1878; application filed 1ebruary 9, 1878.

To all whom it may concern:

Be it known that I, T. B.- DOOLITTLE, of Bridgeport, in the county ofFairfield and State of Connecticut, have invented certain new and usefulImprovements in Tips for Switch-Cords; and I do hereby declare that thefollowing is a full and exact description thereof, reference being hadto the accompanying drawings, making apart of this specilication.

My invention relates to certain new and useful improvements in the tipsfor electric switch-cords, and in the mode of attaching the same. It hasfor its objects simplicity of construction and the perfect and durablecontact and connection between the-cord and tip; and with these ends andobjects in view, my invention consists of a metal shell and a needle orcarrier adapted to carry and hold the core and'end of a cord; and myinvention also consists of the method hereinafter described of producingthe contact'necessary in switchcords to produce perfect conductivity.

Another feature of my invention relates to the novel form of thetip-wire, whereby it may not only be more firmly held in a screw-postthan those of the form heretofore in use, but

- whereby greater electric conductivity between phone-conductors, aswill be hereinafter explained.

Previous to my invention great difficulty has been experienced inarranging the end of the switch-cord core so that it could besuccessfully and durabl y connected with the posts of telephones andwith the switch-plates in telegraph offices, and several novel ideashave been suggested, the most approved and generally used being thejoining of the core with a metal point or bar ,by the use of solder toform the contact, and then covering thesamc with a split-metal cone.

In practice I have found that the connection between the core and metalbar is unreliable and likely to become impaired in use, and that theemployment of solder to form the joint has a tendency to render theconductivity less perfect than .it should be, owing in a measure to thechemical action of the solder acids upon the comparatively small wireswhich are employed in the cores of switchcords.

I have sought by my invention to overcome all these difficultiesanddisadvantages by avoiding the use of solder altogether, and

rendering the contact and conductivity perfect by binding theseveraLpants tightly to-' the advantagesof my invention and learnhow touse the same, I will proceed to describe the construction andapplication of the same, re-

ferring by letters to the accompanying drawin g, in which- 4 Figure 1 isa central longitudinal section of one of my improved, tips as applied tothe end of a. switch-cord, with the cord and carrying-needle shown inelevation, and the latter in two positions, the solid lines showing itin the act of starting it through the forward end of the shell, and thedotted lines showing it in positions longitudinally tobe fastened inplace by crimping the shell. Fig. 2 is a view similar to Fig. 1, butshowing the needle and cord secured permanently in place by the crimpingof the shell. .Fig. 3 is a side elevation of the shell and needledisconnected; Figs. 4, 5, and 6, similar views, showing modi ficationsof theneedle or core carrier; andFi g. 7, a similar view, showing amodification of the mode of orimpingthe needle in place. In the lastfour figures the shell is shown in section to expose the needle andcord.

Similar letters indicate like partslin the several figures.

A is a brass or other suitable sheet-metal shell, made many desirablemanner, and having its open end slightly flared to prevent abrasion ofthe braided covering of the cord. The practically closed or forward endof the shell has a central hole or perforation, adapted to permit thepassage of the needle B, which is formcd,as shown, with an eye, a,through which the eore-wi re is threaded, and enlarged around the eye,as seen. at b, so that the said portion will just fit snugly the insideof the shell A.- Behind the eye a is a short tail, 0. d is the metalcore of the switch-cord, which is composed of a series of small wireswound spirally around a flexible core, or formed 111 any other manner;and c is the braided covering.

At Figs. 1 and 2 Ihave shown the manner of attaehing the tip, whichconsists in first cutting away-the binder and braided covering of thecord, exposing the core (I, which is then ted lines' at Fig. 1 and solidlines at Fig. i,

the relative diameters of the needle proper and the hole in the forwardend of the shell and the swell at the eye and the inside diameter of theshell being such that when drawn to the position shown at Fig. 2 theywill bind snugly. hen the needle is in theposition just described, itwill have drawn the braided portion of the cord within the back edge ofthe shell, and the latter is then, by means of a suitable press, crimpedjust behind the eye of the needle, as shown at f, whereby the core ofthe cord is pinched between the walls of the shell and the needle toproduce perfect contact between the three, and the needle is also firmlyheld in place against vibration, and in order that the braided coveringmay be insured against slipping back upon the core, and also to form asecondary grasp upon the cord as a whole, the shell is also crimped atg. The result of the two erimpin gs accomplishes the objects sought, andmakes a strong, stiif joint and perfect contact of metals. The

. projecting end or point of the needle, iftoo long, may be clipped offat any suitable or desirable distance from the shell.

The form of wire which I preferis rectangular or triangular incross-section, as by reason of such form I am enabled to hold the samemore firmly within the post and obtain more than a single point ofcontact between the tipwire and post; and an additional advantageresulting from such form rests in the fact that the angular needle ortip-wire, in passing through. the round puncture or orifice in the a F-E'ST AVA! LABIIF COP front end of the shell, cuts or spreads the edge ofsaid orifice and induces to a tight fit and close contact.

At Figs. 4, 5 and 6 the needle is shown with difi'erent formations ofthe eye or hook, and these are only designed to show a few of manydifferent ways in which I have applied the principle of my invention,preferring in practice to use the form shown in Figs. 1, 2 and 3. Thepoint of the needle may be bent, as shown in dotted lines at Fig. 5, toadapt it to some kinds of posts. Many other changes will suggestthemselves, which may .bemade without departing from the spirit of myinvention, and I do not therefore wish to'be understood as at alllimiting myself in this direction, nor in the exact point within theshell where the'eyebf the needle is secured, as it may he immediatelyadjacent to the forward end, or at any point' between the front and backends, and the shell crimped behind the eye, or behind and in. .front ofthe same, asclearly shown in Fig. .7, in which case the shell would havea practicalswell between the grooves or crimps'.

I do not wish to be understood as confining myself to a seamless shell,for, although Ipre fer such a shell, they may be made with .alongitudinal seam.

IVhat I claim'as new, and desire to secure by Letters Patent, is-

1. As anew article of manufacture, a tip for switch-cords consisting ofa metallic shell and a metallic needle, the. latter adapted to carry thecore of the cord within the shell, and to be secured in placesubstantially as herein? before described. v 2. As an improved articleof manufacture, a switch-cord provided with a metallic tip, sccured inposition to produce conductivity by compression of the shell,substantially as hereinbefore set forth.

3. The method herein described of securing metal tips to switch-cordsand producing conductivity'by compressing the outer shell and confiningthe core between the said shell and an interior spear or needle.

4.. In combination with an electric switchcord, a tip-wire or needle ofrectangular or triangular form in cross-section, substantially as andfor the purposes set forth.

In testimony whereof I have hereunto set my hand and seal this 8th dayof February,

' T. ILDOOLITTLE. I L. s.] In presence of W11. 0. .MCIN'IIRE, F. W.HOWARD.

